Sentinel Lymph Node Biopsy and Axillary Dissection

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CHAPTER 23 Sentinel Lymph Node Biopsy and Axillary Dissection

Robert E. Roses

Case Study

A 55-year-old male presents for evaluation of a pigmented lesion on his upper mid-back. He notes that the lesion has increased in diameter, has become raised, and has changed coloration over the past several months. He is fair skinned, with blue eyes and blond hair. He reports a history of blistering sunburns as a teenager. An asymmetric lesion with a maximal diameter of 1 cm and variegated brown coloration is noted on his mid-back. He has multiple other pigmented lesions scattered over his trunk and extremities. No adenopathy in his axillae, neck, or groin is appreciated. A punch biopsy shows a malignant melanoma with a thickness of 2.9 mm.

BACKGROUND

Lymph node staging is an important component of the surgical management of both malignant melanoma and breast cancer. Until the 1990s, complete regional lymphadenectomy represented the standard approach to achieving this goal. The development of sentinel lymph node biopsy has allowed for the more limited, selective treatment of regional lymph nodes and has decreased the number of complete regional dissections performed in patients without nodal metastases. This procedure, as it is currently performed, maps the lymphatic drainage from the skin or breast to a primary lymph node or nodes, using a vital blue dye or a radioisotope-labeled tracer. Surgical excision and pathologic evaluation of these nodes for metastases allows for reliable staging and the prediction of additional lymph node metastases. Generally, patients found to have metastases in the sentinel node or nodes (i.e., positive sentinel node biopsy) undergo completion lymphadenectomy. In contrast, patients with negative findings on sentinel lymph node biopsy can safely forgo lymphadenectomy in view of the very low risk of nonsentinel nodal involvement. Sentinel lymph node biopsy also allows a meticulous histologic evaluation of multiple sections augmented by immunohistochemical staining for melanoma-related antigens and cytokeratins for breast cancer. This, not infrequently, allows more precise staging of both diseases.

With few exceptions, the axillary lymph nodes represent the first site of metastasis from melanomas of the upper extremities and upper trunk and cancers of the breast. This chapter focuses on axillary lymph node biopsy; however, the techniques described are applicable to sentinel lymph node biopsy performed at other sites (e.g., the groin for lower extremity melanomas and the cervical, parotid, and occipital lymph nodes for head and neck melanomas). Axillary dissection, which remains an important component of the management of breast cancer and melanoma and typically follows a positive finding on sentinel lymph node biopsy, is also described.

INDICATIONS FOR SURGERY

I. Breast Cancer

A. Patients with invasive breast cancer who can safely undergo surgery benefit from lymph node staging. This is generally achieved through sentinel lymph node biopsy. Exceptions include patients with axillary lymphadenopathy suspicious for metastatic disease and patients who have had previous breast or chest wall irradiation, which may disrupt the lymphatics and preclude accurate lymphatic mapping. Such patients should forgo sentinel lymph node biopsy in favor of axillary dissection. Elderly patients or those with significant comorbidities, with favorable stage I tumors, also may forgo sentinel lymph node biopsy.
B. Although patients with in situ breast cancers should not, theoretically, have nodal metastases, invasive foci in the area of the in situ disease is present in 10% to 30% of patients. A number of indications for sentinel lymph node biopsy in patients with ductal carcinoma of the breast (DCIS) have, therefore, emerged. Sentinel lymph node biopsy is indicated in patients with multicentric or broad areas of high-grade DCIS, as well as in those undergoing total mastectomy (which precludes subsequent nodal staging without axillary dissection).

II. Melanoma is the eighth most common cancer in the United Stated and the most common cause of skin cancer–related deaths. Tumor thickness is the dominant prognostic factor and is correlated with the risk of regional metastasis. Generally, sentinel lymph node biopsy is offered to patients with melanomas exceeding 1 mm in thickness. Completion lymphadenopathy is performed if the sentinel node is found to contain metastatic disease. Patients with “intermediate-thickness” melanomas (1–4 mm) are at relatively higher risk of having nodal metastases compared with patients with thinner lesions, but they are at lower risk, compared with patients with thicker lesions, of having distant metastases. Notably, the therapeutic utility of sentinel lymph node biopsy in patients with such lesions was recently evaluated in the Multicenter Selective Lymphadenectomy Trial. This trial compared wide local excision and sentinel lymph node biopsy with wide local excision alone for the treatment of intermediate-thickness melanomas and demonstrated a survival advantage for patients randomized to the former treatment group who had nodal micrometastases.

PREOPERATIVE EVALUATION

The components of the preoperative evaluation of patients with breast cancer and melanoma are distinct and are discussed separately.

I. Breast Cancer

A. The evaluation of a suspected breast cancer typically includes breast examination, mammography, and breast biopsy. Additional diagnostic modalities increasingly used in the evaluation of breast lesions include ultrasound and magnetic resonance imaging. The goals of this evaluation are to: (1) establish a tissue diagnosis, (2) clinically stage patients, and (3) identify candidates for breast-conserving therapy versus patients who require mastectomy.
B. An assessment for regional metastases should begin with a physical examination of the bilateral axillary and supraclavicular fossae. Adenopathy suggestive of metastatic disease may be further evaluated with fine-needle aspiration; malignant cells seen on cytologic evaluation or a high degree of suspicion for nodal metastases should prompt axillary dissection rather than sentinel lymph node biopsy.

II. Melanoma

A. The evaluation of a suspected melanoma begins with a biopsy to both diagnose and microstage the lesion if proven to be a melanoma. Excisional biopsy (i.e., removal of the lesion with grossly negative margins) is the optimal technique for smaller lesions. A punch biopsy directed at the clinically thickest area is sufficient for larger lesions. Shave biopsies may preclude accurate assessment of tumor thickness and should be avoided. After biopsy, tumor thickness is characterized on the basis of anatomic level of invasion (Clark level) and, most importantly, by thickness in millimeters (Breslow thickness). Subsequent wide excision margins reflect the risk of recurrence and are determined by tumor thickness. Tumors less than 1 mm thick are best excised with 1-cm margins whereas lesions thicker than 1 mm may require initial margins of 2 cm.
B. As in breast cancer, an assessment for regional metastases should begin with a physical examination of the potential draining lymph node basins. In the absence of clinically evident nodal metastases, sentinel lymph node biopsy should be performed in conjunction with wide local excision of the primary tumor.
C. In patients with lesions thicker than 1 mm, a baseline chest radiograph and liver function tests as well as a lactate dehydrogenase level should be obtained. Patients with thicker lesions (≥4 mm) are at relatively high risk for distant metastases. A more rigorous evaluation for metastases, including computed tomography (CT) scans or positron emission tomography and CT scans of the chest, abdomen, and pelvis, should be obtained before surgery.

What is the thickness of the melanoma?

APPLIED ANATOMY AND COMPONENTS OF THE PROCEDURE

See Figure 23-1.

image

Figure 23-1 Schematic division of axillary lymph nodes. The axillary lymph nodes may be divided into three groups. Level I lymph nodes are located between the lateral border of the pectoralis minor muscle and the anterior border of the latissimus dorsi muscle. Level II lymph nodes underlie the pectoralis minor muscle. Level III lymph nodes lie medial to the pectoralis minor muscle.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

Preoperative Considerations

I. Prophylactic antibiotics are not generally administered before sentinel lymph node biopsy. Most surgeons give antibiotics before axillary dissection. The chosen antibiotic should have activity against skin flora (i.e., gram-positive organisms) and should be administered within 1 hour before skin incision.
II. When performed in conjunction with wide local excision or mastectomy, sentinel lymph node biopsy is generally performed first, before surgical disruption of draining lymphatics from the primary tumor.

Patient Positioning and Preparation

I. The patient is placed in the supine position. The axilla is exposed by extending the arm at a 90-degree angle.
II. The sterile preparation should include the axilla and upper arm. When performed in conjunction with a mastectomy, the preparation should also include the ipsilateral breast, extending several inches past the midline, above the clavicle and below the inframammary fold. Laterally, the preparation should extend to the posterior axillary line.

Sentinel Lymph Node Biopsy

I. Radioisotope-labeled tracer (technetium-99m sulfur colloid) is injected 1 or more hours before sentinel lymph node biopsy. In patients with melanomas of the trunk or head and neck, particularly if near the midline, where lymphatic drainage may be ambiguous, lymphoscintigraphy should be performed in the nuclear medicine suite after the injection of tracer. This technique, which tracks the tracer with a scintiscanner as it travels from the injection site to the sentinel node, can be helpful in accurately identifying the laterality or bilaterality of the sentinel nodes (e.g., right vs. left axilla or bilateral axillae). In the operating room, minutes before making the incision, the surgeon injects vital blue dye 10 minutes or more before making the incision (Fig. 23-2). In the patient with melanoma, the tracer and dye are injected intradermally so that they may enter the dermal lymphatics draining the site. In patients with breast cancer, injection may be performed using a number of different approaches, with largely equivalent results; the most common sites for injection include the peritumoral breast parenchyma and the subareolar breast parenchyma.

image

Figure 23-2 Blue dye or radioisotope isotope injection at the site of cancer.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

Lymphatics of the breast drain centripetally to the subareolar plexus and then to the axilla.

II. A gamma probe is calibrated and placed on the surgical field in a sterile sheath to allow for subsequent localization of the radioisotope-labeled tracer.
III. A transverse incision is made just below the hair-bearing area of the axilla.
IV. The incision is carried down to the clavipectoral fascia, which is divided.
V. Blue-stained lymphatics are identified. The gamma probe may be used to help direct the surgeon toward the area of maximal uptake (Fig. 23-3).
VI. Blue channels are traced proximally and distally to identify blue nodes with high radioisotope counts (as detected by the gamma probe).
VII. When identified, these “hot and blue” nodes are gently delivered into the field and excised.
VIII. The site of excision is examined with the gamma probe for the presence of residual radioactivity. Nodes with radioactivity greater than 10% of that measured in the sentinel node should be excised as well.
IX. The site is examined for any apparent or palpable lymphadenopathy.
X. Hemostasis is confirmed, and the incision is closed.

image

Figure 23-3 A blue-stained lymphatic and lymph node are identified with the aid of a gamma probe.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

Failure to identify a sentinel node should prompt axillary dissection.

Axillary Dissection

I. A curvilinear incision is made just below the hair-bearing area of the axilla, extending laterally to the posterior axillary line and medially no further than the lateral edge of the pectoralis major muscle.
II. Flaps are developed beneath the subcutaneous layer, extending medially to the edge of the pectoralis major muscle, superiorly to its tendinous insertion, inferiorly to the level of the sixth rib, and posteriorly to the edge of the latissimus dorsi (Fig. 23-4).
III. Medial retraction of the pectoralis major allows for the identification of the lateral edge of the pectoralis minor muscle. The medial pectoral nerve is identified lateral to the pectoralis minor muscle and preserved.

image

Figure 23-4 Flaps are elevated to expose the axilla.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

The medial pectoral nerve innervates the pectoralis minor muscle. Frequently, a branch also innervates the lateral pectoralis major muscle.

IV. The clavipectoral fascia, contiguous with the pectoralis minor fascia, is opened parallel to the lateral edge of the muscle, exposing the lymphadipose contents of the axilla.
V. Superior and medial retraction of the pectoralis muscle and inferior traction on the lymphadipose tissue allow for exposure of the axillary vein.
VI. Lymphatic dissection proceeds along the axillary vein, beginning medially beneath the pectoralis minor muscle (level II nodes) and proceeding laterally (Fig. 23-5).
VII. As the dissection proceeds, the inferior axillary contents are dissected off the serratus anterior fascia.
VIII. The intercostobrachial nerve is identified as it exits the second intercostal space and is preserved, if possible.

image

Figure 23-5 Axillary dissection proceeds from level II laterally.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

TRANSECTION OF THE INTERCOSTOBRACHIAL NERVE RESULTS IN PARESTHESIAS OF THE SKIN OF THE AXILLA AND MEDIAL ARM.

IX. As the dissection is carried toward the junction of the serratus anterior and subscapularis muscles, lateral intercostal perforating vessels are divided and ligated.
X. The long thoracic nerve is identified as it courses superficial and lateral to the serratus anterior muscle, and is preserved.

INJURY TO THE LONG THORACIC NERVE RESULTS IN A WINGED SCAPULA DEFORMITY BECAUSE OF THE RESULTANT PARALYSIS OF THE SERRATUS ANTERIOR MUSCLE.

XI. The thoracodorsal nerve and vessels are identified as they course over the subscapularis muscle and are preserved (Fig. 23-6). The remaining lateral axillary contents are dissected with the specimen, which is transected at the border of the latissimus dorsi muscle.
XII. A closed-suction drain is placed within the axilla and brought out through a stab wound beneath the inferior flap.
XIII. The incision is closed, typically in two layers (subcutaneous and subcuticular).
image

Figure 23-6 The intercostobrachial, long thoracic, and thoracodorsal nerves are identified and preserved as dissection proceeds laterally to the anterior border of the latissimus dorsi muscle.

(From Roses DF [ed]: Breast Cancer, 2nd ed. Philadelphia, Churchill Livingstone, 2005.)

POSTOPERATIVE COURSE

Sentinel lymph node biopsy can be performed on an outpatient basis and is rarely associated with significant postoperative pain. Hospital admission, however, may be required when sentinel lymph node biopsy is performed in conjunction with a more extensive procedure to treat the primary tumor (e.g., total mastectomy). In contrast, axillary dissection may necessitate hospital admission to ensure early pain control and appropriate observation. Closed-suction drains are typically maintained for approximately 1 week. Many surgeons advocate continuation of antibiotic prophylaxis while the drain is maintained. In the immediate postoperative period, patients are encouraged to gently elevate the ipsilateral arm to maintain range of motion. Full range-of-motion exercises are usually delayed until the drain has been removed and the skin becomes adherent to the underlying axillary hollow because vigorous exercise may exacerbate seroma formation. Application of a blood pressure cuff and needle sticks are avoided on the ipsilateral arm, although the likelihood of promoting lymphedema with such interventions is low.

COMPLICATIONS

Complications of sentinel lymph node biopsy are unusual; surgical site infection, although rare, is the most common. Axillary dissection may be associated with several complications.

I. Seroma formation is anticipated after axillary dissection. Accumulation may be minimized through maintenance of closed-suction drainage for the first week after surgery. Seroma formation after the drain is removed may be managed by aspiration.
II. Lymphedema, manifested by swelling or heaviness of the ipsilateral arm, is not uncommon after axillary dissection, with an incidence of 5% to 25%. In most cases, lymphedema is subtle; obvious or disabling enlargement is uncommon. Radiation therapy (for breast cancer) and obesity are contributory factors. Arm elevation, weight loss, and the use of elastic pressure-graded sleeves may be helpful.
III. Lymphangiosarcoma is a rare, but devastating, complication associated with chronic lymphedema, and is heralded by vascular-appearing nodules in the edematous extremity (Stewart-Treves syndrome). The mean interval between surgery and the diagnosis of lymphangiosarcoma is 10 years. Therapy may include wide local excision or even amputation. Unfortunately, the prognosis is very poor, with a median survival of 2 years.
IV. Nerve injury may result from axillary dissection. Nerves at risk include the intercostobrachial, long thoracic, thoracodorsal, and medial pectoral. Division of the intercostobrachial nerve results in numbness or paresthesias of the upper medial nerve and axilla. These symptoms often resolve over months because of the rich sensory innervation of the area. Division of the long thoracic nerve results in a winged scapula from paralysis of the serratus anterior muscle, whereas division of the thoracodorsal nerve results in limitation of backward motion of the extended arm from denervation of the latissimus dorsi muscle. Division of the medial pectoral nerve may result in atrophy of the lateral pectoralis major muscle.

SUGGESTED READINGS

Lange JR, Balch CM. Cutaneous melanoma. In Cameron JL, editor: Current Surgical Therapy, 8th ed, Philadelphia: Mosby, 2004.

Morton DL, Thompson JF. Sentinel-node biopsy or nodal observation in melanoma. N Engl J Med. 2006;355:1944.

Roses DF, Guiliano AE. Surgery for breast cancer. In Roses DF, editor: Breast Cancer, 2nd ed, Philadelphia: Churchill Livingstone, 2005.

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CHAPTER 23 Sentinel Lymph Node Biopsy and Axillary Dissection

Robert E. Roses

Case Study

A 55-year-old male presents for evaluation of a pigmented lesion on his upper mid-back. He notes that the lesion has increased in diameter, has become raised, and has changed coloration over the past several months. He is fair skinned, with blue eyes and blond hair. He reports a history of blistering sunburns as a teenager. An asymmetric lesion with a maximal diameter of 1 cm and variegated brown coloration is noted on his mid-back. He has multiple other pigmented lesions scattered over his trunk and extremities. No adenopathy in his axillae, neck, or groin is appreciated. A punch biopsy shows a malignant melanoma with a thickness of 2.9 mm.

BACKGROUND

Lymph node staging is an important component of the surgical management of both malignant melanoma and breast cancer. Until the 1990s, complete regional lymphadenectomy represented the standard approach to achieving this goal. The development of sentinel lymph node biopsy has allowed for the more limited, selective treatment of regional lymph nodes and has decreased the number of complete regional dissections performed in patients without nodal metastases. This procedure, as it is currently performed, maps the lymphatic drainage from the skin or breast to a primary lymph node or nodes, using a vital blue dye or a radioisotope-labeled tracer. Surgical excision and pathologic evaluation of these nodes for metastases allows for reliable staging and the prediction of additional lymph node metastases. Generally, patients found to have metastases in the sentinel node or nodes (i.e., positive sentinel node biopsy) undergo completion lymphadenectomy. In contrast, patients with negative findings on sentinel lymph node biopsy can safely forgo lymphadenectomy in view of the very low risk of nonsentinel nodal involvement. Sentinel lymph node biopsy also allows a meticulous histologic evaluation of multiple sections augmented by immunohistochemical staining for melanoma-related antigens and cytokeratins for breast cancer. This, not infrequently, allows more precise staging of both diseases.

With few exceptions, the axillary lymph nodes represent the first site of metastasis from melanomas of the upper extremities and upper trunk and cancers of the breast. This chapter focuses on axillary lymph node biopsy; however, the techniques described are applicable to sentinel lymph node biopsy performed at other sites (e.g., the groin for lower extremity melanomas and the cervical, parotid, and occipital lymph nodes for head and neck melanomas). Axillary dissection, which remains an important component of the management of breast cancer and melanoma and typically follows a positive finding on sentinel lymph node biopsy, is also described.

INDICATIONS FOR SURGERY

I. Breast Cancer

A. Patients with invasive breast cancer who can safely undergo surgery benefit from lymph node staging. This is generally achieved through sentinel lymph node biopsy. Exceptions include patients with axillary lymphadenopathy suspicious for metastatic disease and patients who have had previous breast or chest wall irradiation, which may disrupt the lymphatics and preclude accurate lymphatic mapping. Such patients should forgo sentinel lymph node biopsy in favor of axillary dissection. Elderly patients or those with significant comorbidities, with favorable stage I tumors, also may forgo sentinel lymph node biopsy.
B. Although patients with in situ breast cancers should not, theoretically, have nodal metastases, invasive foci in the area of the in situ disease is present in 10% to 30% of patients. A number of indications for sentinel lymph node biopsy in patients with ductal carcinoma of the breast (DCIS) have, therefore, emerged. Sentinel lymph node biopsy is indicated in patients with multicentric or broad areas of high-grade DCIS, as well as in those undergoing total mastectomy (which precludes subsequent nodal staging without axillary dissection).

II. Melanoma is the eighth most common cancer in the United Stated and the most common cause of skin cancer–related deaths. Tumor thickness is the dominant prognostic factor and is correlated with the risk of regional metastasis. Generally, sentinel lymph node biopsy is offered to patients with melanomas exceeding 1 mm in thickness. Completion lymphadenopathy is performed if the sentinel node is found to contain metastatic disease. Patients with “intermediate-thickness” melanomas (1–4 mm) are at relatively higher risk of having nodal metastases compared with patients with thinner lesions, but they are at lower risk, compared with patients with thicker lesions, of having distant metastases. Notably, the therapeutic utility of sentinel lymph node biopsy in patients with such lesions was recently evaluated in the Multicenter Selective Lymphadenectomy Trial. This trial compared wide local excision and sentinel lymph node biopsy with wide local excision alone for the treatment of intermediate-thickness melanomas and demonstrated a survival advantage for patients randomized to the former treatment group who had nodal micrometastases.

PREOPERATIVE EVALUATION

The components of the preoperative evaluation of patients with breast cancer and melanoma are distinct and are discussed separately.

I. Breast Cancer

A. The evaluation of a suspected breast cancer typically includes breast examination, mammography, and breast biopsy. Additional diagnostic modalities increasingly used in the evaluation of breast lesions include ultrasound and magnetic resonance imaging. The goals of this evaluation are to: (1) establish a tissue diagnosis, (2) clinically stage patients, and (3) identify candidates for breast-conserving therapy versus patients who require mastectomy.
B. An assessment for regional metastases should begin with a physical examination of the bilateral axillary and supraclavicular fossae. Adenopathy suggestive of metastatic disease may be further evaluated with fine-needle aspiration; malignant cells seen on cytologic evaluation or a high degree of suspicion for nodal metastases should prompt axillary dissection rather than sentinel lymph node biopsy.

II. Melanoma

A. The evaluation of a suspected melanoma begins with a biopsy to both diagnose and microstage the lesion if proven to be a melanoma. Excisional biopsy (i.e., removal of the lesion with grossly negative margins) is the optimal technique for smaller lesions. A punch biopsy directed at the clinically thickest area is sufficient for larger lesions. Shave biopsies may preclude accurate assessment of tumor thickness and should be avoided. After biopsy, tumor thickness is characterized on the basis of anatomic level of invasion (Clark level) and, most importantly, by thickness in millimeters (Breslow thickness

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